The present invention is directed to devices for receiving and discharging fluids. Devices embodying features of the present invention include, by way of example, without limitation, tees, unions, fittings, valves and check valves. These devices are sometimes placed in line between two or more conduits that are joined in the form of a union, or tee, or valve. The term “union” is used in the sense of joining or bringing together. A “tee” is a form of fitting in which fluid flow is split or combined. The devices are sometimes part of a larger structure in which the device communicates through ports or openings. This application will use the term “fluid path means” to mean all conduits, tubing, pipes, openings or ports which convey or transport fluids.
In this application, the term fitting will be used in the broadest sense to refer to a device that may be placed in a larger structure, for example, a pump assembly, or in line.
The term “valve” is used in a conventional manner to denote a device that can stop fluid flow in a conduit or pipe. A check valve is a special valve that allows fluid to flow in one direction only.
Fitting and valves of the prior art typically have gaskets and seals that are separate and discrete parts. These gaskets and seals exhibit material creep, cold flow and relaxation. That is, as the fluid pressure fluctuates, the gaskets move. This movement can lead to the gasket slipping from an original position, leading to gasket or seal failure.
This movement also creates a rebound of the gasket as the pressure is released, creating a potential pressure ripple. Analytical instruments, in particular, are sensitive to the rebound and pressure ripple effect.
These problems are amplified as the pressure contained by such devices increases. Analytical instruments, such as chromatography pumps and detectors typically operate at pressures of up to 3,000 to 4,000 pounds per square inch (psi). It is desirable to have analytical instruments operate at higher pressures, however, fittings, valves and check valves have a high failure rate at pressures greater than 3,000 psi.